Interventional catheters incorporating aspiration and/or infusion systems

ABSTRACT

An interventional catheter assembly comprising a catheter for insertion and guidance to a target site in a body lumen or a cavity and an operating head mounted in proximity to a distal end of the catheter and comprising a system for removing obstructive material from the target site is provided. In certain embodiments, the catheter assembly includes at least one aspiration port located proximal to the operating head that communicates with a first sealed lumen for withdrawing fluids and obstructive material from the target site, together with at least one liquid infusion port penetrating the catheter and located proximal to the at least one aspiration port that communicates with a second sealed lumen for supplying fluid to a location in proximity to the target site.

REFERENCE TO PRIORITY APPLICATIONS

This application claims priority to U.S. provisional patent applicationNos. 60/894,173 filed Mar. 9, 2007, and 60/828,209 filed Oct. 4, 2006.The disclosures of these priority applications are incorporated byreference herein in their entireties.

FIELD OF THE INVENTION

The present invention relates to methods and systems for removingmaterial, such as obstructions and partial obstructions, from aninternal lumen or cavity of a mammalian subject, such as a blood vessel.More particularly, the present invention relates to interventionalcatheters having operating heads incorporating aspiration and/orinfusion systems for withdrawal of liquids and debris from a site ofintervention and introduction of fluids to the site.

BACKGROUND OF THE INVENTION

Removal of disease such as atherosclerotic plaque, thrombus and othertypes of obstructions and partial obstructions from internal body lumensor cavities using advanceable, rotating operating heads having cutterassemblies or abrasive materials is a well-established interventionaltechnique. Numerous interventional catheters have been conceived anddeveloped. Most of these systems require placement of a guide wire andguiding catheter prior to introduction of the interventional catheterand placement of the interventional catheter at the target operatingsite. Many of these prior art systems incorporate vacuum aspirationsystems to remove the ablated material from the site, thereby preventingdistal embolization. Some interventional catheters additionally oralternatively incorporate or are used in conjunction with othermechanisms, such as distal filters, for preventing removed material fromcirculating in the blood stream. Numerous interventional catheters alsoprovide infusion of a liquid to the site of the intervention. Infusedliquids may assist in the material removal process, or may be providedas diagnostic or therapeutic materials prior to, during or following anintervention.

Devices for collecting undesired material from a site in a body lumen orcavity, such as a blood vessel, that employ material excision devicesincorporating a blade, barb, screw, or another material capturemechanism, to draw material into a device cavity are also known. Thesematerial capture mechanisms may be provided on a non-rotating or arotating operating head. Non-cutting and non-mechanical systems forremoving material from body lumens and blood vessels, such as heat,ultrasound and laser ablation systems, have also been developed.

Despite the many and varied approaches to the material removal systems,many challenges remain in providing systems for removing material from alumen, such as a blood vessel, safely and reliably and without causingcomplications. The safety and reliability of the system is manifestlycritical. Recovery of debris generated during a material removaloperation, or reducing the particle size of the debris to a particlesize that will not damage blood vessels or produce embolic events, isessential. The flexibility and size of an interventional catheter arealso important features. The system must be small enough and flexibleenough to navigate through sometimes tortuous internal structures andpassageways for placement at the target interventional site. Maintainingdesired fluid infusion rates and pressures, system flexibility andeffective aspiration capacity while withdrawing debris through a long,small diameter catheter presents numerous challenges.

SUMMARY OF INVENTION

The present invention provides interventional catheters that may beemployed to rapidly and effectively remove unwanted material from bodylumens or cavities. Interventional catheters and control systemsdisclosed herein may be adapted for use within a variety of body lumensor cavities such as blood vessels and vascular cavities,gastrointestinal cavities, lumens or cavities in the urinary system andin male and female reproductive organs, and other fluid cavities such aspulmonary lumens and gas exchange cavities, nasal and sinus cavities andthe like. The lumen or cavity may form a generally tubular structure,such as a blood vessel, a ureter, a fallopian tube, a nasal passageway,and other tubular passageways. For example, systems of the presentinvention may be used for removing undesired material from native bloodvessels such as native coronary, renal, cranial, peripheral and otherblood vessels, artificial or grafted vessels such as saphenous veingrafts, and the like. The lumen may have implanted devices such asstents in place. The lumen or cavity may be within, or in proximity to,an organ such as a kidney, gall bladder, lung or the like, or the bodycavity may form part of another system, such as a lymph node, spinalcanal, or the like. Interventional catheters are generally used toremove unwanted material from a target site in body lumens or cavitiesof mammalian subjects, particularly human patients.

The undesired material that is removed using interventional catheterassemblies and control systems disclosed herein may be disease materialsuch as atherosclerotic plaque, calcified plaque, thrombus, or othertypes of deposits, gallstones, a valve or portion thereof, and the like.In certain embodiments, the interventional catheter assemblies disclosedherein are employed in the treatment of cardiovascular or peripheralartery disease (PAD) to remove disease material from blood vessels,including peripheral blood vessels.

The present interventional catheter assembly includes a catheter systemthat is at least partially inserted and navigated within a patient'sbody while an operator controls the system externally of the patient'sbody. A control module housing aspiration and/or infusion systems,providing power to a downstream interventional catheter controller, andproviding various control and display features may also be provided. Theinterventional catheters disclosed herein incorporate a material removalcomponent, referred to herein as an “operating head,” which is generallypositioned at or near the distal end of the interventional cathetersystem. As used herein, “proximal” refers to a direction toward thesystem controls and the operator along the path of the catheter system,and “distal” refers to the direction away from the system controls andthe operator along the path of the catheter system toward or beyond aterminal end of the operating head.

Fluidic communication between the operating head and externallypositioned components of the interventional catheter system is generallyprovided by one or more sealed passageways of the catheter system. Othertypes of communication systems or pathways may also be provided fordelivery of power, for rotationally driving and translating theoperating head, for implementing various control features, and the like.The operating head may be driven, or controlled, using electricalsystems, radio frequency and other remote control systems, mechanicalsystems, magnetic systems and other systems or modalities suitable forremote operation of an operating head. The operating head may alsoincorporate features providing additional functionalities such asultrasound guidance, various types of imaging features, and the like.The system components described below are described as exemplarycomponents and are not intended to limit the scope of the invention.

The interventional catheter system may be used in conjunction with aflexible guidewire that is navigated through internal pathways, such asblood vessels, to a target material removal site. For partialobstructions, the guidewire is generally placed across the lesion andthe operating head of the interventional catheter is advanced on theguidewire to the target site and then operated into and through thelesion. When a lumen is totally obstructed and a guidewire cannotpenetrate the obstruction without causing harm to nearby tissue orrisking embolization, the operating head may be advanced beyond thedistal tip of the guidewire and into and through the obstruction, or theoperating head and guidewire may be advanced in tandem. Other methodsthat may be employed for guiding and steering the operating headinclude, but are not limited to, radio frequency systems, stereotacticsystems, magnetic systems, remote control systems, and the like. Theinterventional catheters disclosed herein may be adapted for use withany of these steering systems.

The operating head may take any of a variety of forms. In oneembodiment, the operating head is rotatable and incorporates cutterelements. Rotational operating heads are generally operably connected toa rotatable drive shaft and catheter system, and drive system andcontrol systems and, in embodiments described herein, comprise at leastone distally located cutter assembly, wherein the cutter assemblyincludes at least one cutting, or scraping or abrading surface, referredto as a cutting surface or blade. Although the “cutting” or “cutter”surfaces or blades of an interventional catheter of the presentinvention may be sharp and may actually “cut” material at the targetsite, the term “cut” or “cutting” or “cutter” or “blade(s),” as usedherein, refers to cutting, scraping, abrading, ablating, macerating andotherwise breaking down undesired material into particles or smaller,removable, units of material.

In some embodiments, interventional catheters incorporate cutterassemblies comprising a plurality of cutting blades and may incorporatefixed and/or adjustable blades. Suitable cutter assemblies aredisclosed, for example, in U.S. Pat. Nos. 6,565,588 and 6,818,001, whichare incorporated herein by reference in their entireties. Differentialcutting blades are preferred for use in many applications and suitabledifferential cutting blades are disclosed, for example, in U.S. PatentPublication 2004/0006358 A1, which is incorporated herein by referencein its entirety. In some embodiments, the operating head may comprise anabrasive surface or an abrasive material provided on a surface of ablade or another rotational element. Rotational elements incorporatingabrasives are well known in the art. In an alternative embodiment, theoperating head may comprise another type of ablation device, such as aplaque excision device, a laser ablation or high frequency ultrasoundablation device, or a radio frequency or heat-producing or electricaldevice that operates to remove unwanted material from body lumens orcavities and generally does not rotate during operation. These ablationdevices are also well known in the art.

In applications employing rotational operating heads, the drive shaftthat conveys rotation and torque from a drive system to the operatinghead is small enough and flexible enough to be navigated through smalland tortuous passageways during navigation of the operating head to thetarget removal site. It also has sufficient mechanical integrity totransfer high rotational and torque loads, and operate in a high vacuum,or aspirate withdrawal, environment. Multi-filar helical coils are usedas drive shafts in many types of interventional catheters having arotatable operating head. Suitable drive shafts are well known in theart and are described in the patent publications incorporated herein byreference.

The drive shaft is carried in a flexible catheter structure and mounted,directly or indirectly, to the operating head to rotate the operatinghead. The rotational operating head and drive shaft may be directly orindirectly connected to the flexible catheter structure by means of abearing near the distal end, such that the catheter remains stationaryduring operation of the operating head, while the operating head isrotated by the drive shaft. Alternatively, the operating head and driveshaft may be independent of the catheter at its distal end, such thatthe operating head is rotatable and axially translatable independent ofthe catheter assembly.

Interventional catheters disclosed herein preferably incorporate anaspiration system for removal of debris from the intervention site bymeans of aspiration through one or more aspiration ports. Aspirationsystems suitable for use in interventional catheters of the presentinvention are described, for example, in the patents incorporated hereinby reference and in U.S. Patent Publication 2004/0220519 A1, which isalso incorporated herein by reference in its entirety. Debris generatedduring a material removal operation is entrained in fluids (e.g. blood),and the aspirate fluid containing debris is removed through the materialremoval port(s) and withdrawn through a sealed lumen of theinterventional catheter.

In one embodiment of interventional catheters of the present invention,at least one large aspiration port is provided in proximity to, andpreferably proximal to, the operating head. Debris generated during amaterial removal operation is entrained in fluids (e.g. blood), and theaspirate fluid containing debris is withdrawn through the proximalaspiration port(s) and conveyed through a sealed lumen of theinterventional catheter to an aspirate conduit for discharge in anaspirate collection system. Additional, generally smaller, materialremoval ports may also be disposed on one or more surfaces of theoperating head itself.

Liquid infusion may also be provided in proximity to the operating head.Infusion of liquids may be used to provide additional liquid volume forremoval of debris, or to deliver lubricating fluids, diagnostic ortreatment agents, contrast agents and the like. Infusion of fluids suchas saline in proximity to the target material removal area may bedesirable because it tends to reduce the viscosity of the materialsbeing removed, thus facilitating removal through relatively smalldiameter lumens. Infusion of liquids also desirably tends to reduce thevolume of blood removed during a material removal operation, therebyreducing blood loss and allowing longer procedures. In addition,infusion of liquids reduces vessel collapse and keeps the vessel wall intension, thereby improving the effectiveness of cutting operations andreducing damage to the vessel wall. Liquid infusion may also reduceguidewire friction in embodiments where guidewires are employed. Liquidinfusion may be provided distal or proximal to the operating head,and/or may be provided through the operating head.

Many different types of infusion systems are known and may be used ininterventional catheters of the present invention. In one embodiment,multiple infusion ports are arranged to provide a substantially evendistribution of infusate around the circumference of the device, whilein alternative embodiments, one or more infusion ports may be providedto distribute infusate in a directed manner at one or more locationsaround the circumference of the device. A plurality of fluid infusionports are provided in an outer sheath mounted over a distal catheterportion and positioned proximal to the operating head in one embodiment.Infusion may additionally or alternatively be provided through ports inthe operating head.

In general, interventional catheters of the present invention operate toprovide a volume ratio of infusate to aspirate of greater than about1:1. For example, the volume ratio of infusate to aspirate may greaterthan 1.5:1 and less than about 2.5:1. Infusion and aspiration rates mayalso be controlled within desired ranges, and several monitoring andcontrol features may be provided. In one embodiment, for example, abubble detection mechanism is provided to detect a bubble in theinfusion conduit and inactivate the infusion pump and/or power to theoperating head upon detection of a bubble. In another embodiment, theinfusion and aspiration systems are activated automatically uponactivation of the operating head, or after a delay period followingactivation of the operating head. In yet another embodiment, theinfusion and aspiration systems are may also be inactivatedautomatically upon inactivation of the operating head, or after a delayperiod following inactivation of the operating head.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of an interventional catheter assemblyhaving aspiration and infusion systems and comprising an operating headmounted at or near a distal end of a catheter system, a controller and aconsole unit.

FIG. 2 is an enlarged diagram illustrating the distal end of aninterventional catheter of the present invention incorporating anoperating head with aspiration and/or infusion ports and a proximal portfor aspiration and/or infusion.

FIG. 3 is an enlarged diagram illustrating the distal end of aninterventional catheter of the present invention incorporating anoperating head, an aspiration port located proximally of the operatinghead, and a plurality of infusion ports located proximally to theaspiration port.

DETAILED DESCRIPTION

Certain preferred embodiments are described herein with reference to amaterial removal device having a rotating operating head that removesundesired material using a cutting mechanism. It will be appreciatedthat this device embodiment is being described as illustrative and thatthe inventions and features disclosed herein are applicable tointerventional catheters having different types of operating heads,including generally static operating heads using non-cutting mechanismsof material removal.

FIG. 1 illustrates an exemplary embodiment of an interventional catheterassembly, including a console unit incorporating aspiration and infusionsystems as disclosed herein. Interventional catheter assembly 10comprises console unit 12, controller 30, and catheter system 32 havingan operating head 40 located at or in proximity to the distal end of thecatheter system. Controller 30 may be used to manipulate (e.g. advanceand/or rotate) the catheter system 32 and operating head 40, oralternative controls may be provided. The configuration of the operatinghead and aspiration and infusion ports provided in association with theoperating head will be described below with reference to FIGS. 2 and 3.

Console unit 12 incorporates an infusion pump 14 and an aspiration pump16. During operation of the interventional catheter, an infusate conduit18 draws fluid from an infusate reservoir 20 and operably contacts theinfusion pump 14 to provide fluid through an infusion lumen in cathetersystem 32 to one or more infusion ports provided in proximity to theoperating head. Similarly but in reverse, fluids with entrainedparticulates are withdrawn from the site of intervention through anaspiration lumen in catheter system 32 and conveyed to aspirationconduit 22, which is in operable contact with the aspiration pump 16,and communicates with the aspirate collection vessel 24. Console unit 12may also provide a power source for operating the operating head andsystem components, or it may be in communication with an external powersource. In the illustrated embodiment, console unit 12 provides power tothe interventional catheter assembly and controller 30 by means of adevice power port 25 and power cord 26.

Various microprocessor, electronic components, software and firmwarecomponents may be provided within or in communication with the consoleunit for controlling operation of the interventional catheter asdescribed herein. Software may be provided in a machine-readable mediumstoring executable code and/or other data to provide one or acombination of mechanisms to process user-specific data. Alternatively,various systems and components may be controlled using hardware orfirmware implementations. Data storage and processing systems may alsobe provided in console unit 12. Console unit 12 is generally provided asa reusable assembly and is generally operated outside the sterile field.It may be mountable on a portable stand to facilitate convenientplacement during interventions.

One function of console unit 12 is to provide feedback of system and/orenvironmental conditions or operating parameters. The console unit mayoutput operational information concerning operating conditions andfeedback from the material removal site to the operator. According toone embodiment, console unit 12 provides continuously updated output toan operator of operating parameters such as operating head rotationrate, which may include the actual run speed as well as the desiredspeed; operating head advance rate; aspiration rate and/or volume;infusion rate and/or volume; length of the body or matter to be removedthat is traversed; and the like.

Certain automated and selectable control features may be implemented inconsole unit 12. Preset routines or programs involving various operatingparameters may be preselected, stored and selectable by an operator, forexample. Thus, according to one embodiment, the disclosed materialremoval system implements control features based on an operator's inputof specified parameters. Specified parameters may include, for example:lesion length, lesion type and character, such as calcified, fibrotic,lipid/fatty and the like; historical factors, such as restenosis; rateof blood flow; volume of blood flow; percentage of restriction; lumentype and/or location; lumen diameter; desired rotation rate and/orrotation profile for the cutter assembly; desired advance rate and/oradvance profile for the cutter assembly; desired aspiration rate and/orprofile; desired infusion rate and/or profile; and the like. Based onthe specified parameters input by the operator, the control unit maycalculate and implement automated operating conditions, such as: cutterassembly rotation rate and profile; cutter assembly advance rate andprofile; aspiration rate and profile; infusion rate and profile; cutterassembly size; and the like. Various system operating parameters,operating conditions, patient conditions, and the like may also berecorded and stored during interventions to preserve a record of thepatient and intervention operational parameters.

High efficiency aspiration is important in the interventional cathetersystems disclosed herein. In certain embodiments, fluid and associatedparticulates are aspirated from the intervention site at rates of atleast 15 ml/min of operating head run time and, in many embodiments,fluid and associated particulates are aspirated at rates of at least 25ml/min of operating head run-time. In exemplary interventional cathetersystems, the aspiration site may be more than a meter away from thecontroller 30 through an aspirate removal passageway located within thecatheter system 32 and having a diameter of less than 0.10 inch, forexample between about 0.050 to 0.070 inch. The distance that theaspirate travels between controller 30 and console unit 12 may be fromabout ½ meter to several meters, through an aspirate conduit that isbetween about 0.125 to about 1.0 inch in diameter. The blood and debrisbeing aspirated are relatively viscous fluids, and achieving arelatively constant and high level of aspiration under these conditionsis essential.

In one embodiment, aspiration pump 16 comprises a multi-lobed rollerpump. The rotation rates of multiple rollers, or of a multi-lobedrotating structure, may be variable or selectable to control theaspiration rate and volume. Roller pumps permit fluid to flow in aconduit through the rollers of the pump at atmospheric pressure, andthus reduce or prevent the formation of bubbles and foam in the liquidbeing evacuated. Because the aspirate is at atmospheric pressure when itexits the roller pump, a simplified, atmospheric pressure collectionvessel may be used rather than an evacuated collection vessel. A simplebag or another collection vessel, such as those used for collection ofblood, may be used. For example, a collection bag 24 and a sealedaspiration conduit may be provided as part of a sterile disposableinterventional catheter kit. A distal end of the aspiration conduit maybe pre-mounted on and sealed to the controller 30. A proximal portion ofthe aspiration conduit is mounted on the aspiration pump prior tooperation of the interventional catheter and the aspirate collection bagis mounted to or in proximity to the control module.

Infusion pump 14 may also comprise a multi-lobed roller pump employingvariable or selectable rotation rates to control the infusion rate andvolume. A simple bag or another infusate reservoir, such as those usedfor intravenous infusions, may be used to supply the infusate. Forexample, an infusate reservoir 20 having a sealed conduit that ismounted in the infusion pump 16 during operation of the interventionalcatheter may be provided. In this embodiment, the sealed infusateconduit may be provided as part of the sterile disposable interventionalcatheter system and a distal end of the infusate conduit may bepre-mounted on and sealed to the controller 30. A proximal portion ofthe infusate conduit may be connected to an infusate reservoir, such asa saline bag, and mounted in proximity to the infusion pump prior tooperation. A bubble detector 15 may be provided in association withconsole unit 12 and infusate conduit 18 to detect the presence of gasbubbles in the infusate. A control feature that automatically disablesthe infusion pump and/or power to the operating head may be activatedupon detection of a fault (e.g. a bubble) in the infusate conduit.

Console unit 12 may also have control switches for activating andshutting down the aspiration pump and system, and for activating andshutting down the infusion pump and system. These control features maybe provided as simple on/off switches. Alternatively, systems providingdifferent levels or rates of aspiration and/or infusion that areselectable by an operator may be provided. In addition, console unit 12may be provided with a timing mechanism that determines, and displays,the elapsed time of operation of the operating head and/or theaspiration and infusion systems. The volumes of aspirate withdrawn andthe volume of infusate introduced may also be detected and displayed byconsole unit 12. Detection systems for monitoring the levels of aspirateand infusate in the respective reservoirs may be incorporated and alarmsindicating an overfill condition for the aspirate collection system or alow supply condition for the infusate reservoir may be provided. Back-upaspirate collection and infusate supply systems may also be provided.

In one embodiment, console unit 12, together with aspiration pump 16,infusion pump 14 and the associated control and display features, isprovided as a separate, re-usable unit, that may be used as standardequipment in operating rooms, for example. In the system illustrated,console unit 12 is not contaminated by contact with blood or aspirateduring operation, and the power and control systems are durable andlong-lasting and may be reused for many interventions. Console unit 12may be provided in a housing designed to sit on a platform duringoperation, or the housing may be designed for mounting on a portablestructure, such as an i.v. pole or another structure. The interventionalcatheter system, comprising the catheter system 32 with operating head40, the controller 30, aspirate conduit 22, aspirate collection vessel24, and infusate conduit 18 may be provided as a sterile, single usesystem kit.

The catheter system and operating head are described below with areference to a rotatable operating head employing a cutting materialremoval mechanism. In this application, aspiration and infusion conduitsterminate at or within controller 30, where they communicate withaspiration and infusion lumens within the catheter system 32. Arotatable drive shaft for driving the operating head is provided incatheter system 32. A guidewire may also transit controller 30 andcatheter system 32. In general, controller 30 or an associated controlmechanism provides user-operated mechanisms for rotating and/ortranslating the operating head. Controller 30, which is constructed froma durable, sterilizable material, such as hard plastic, may be providedin any convenient ergonomic design and constructed for placement inproximity to and/or in contact with the external body. In oneembodiment, the controller may include an integrated handle for operatorconvenience in holding and supporting the controller during operation.Catheter system 32, exiting controller 30, is axially translatable withrespect to controller 30 as the operating head and catheter system areguided to a target material removal site. It will be appreciated thatsome of the control and operational features described herein withreference to controller 30 may be provided in console unit 12 and,likewise, some of the control and operational features described withreference to console unit 12 may be provided in controller 30.

The operating head 40 of the interventional catheter disclosed hereinmay comprise any of a variety of rotational cutting devices orassemblies having one or more cutting surface(s) for cutting,fragmentizing, pulverizing, ablating, scraping, grinding or otherwisereducing the size of undesired material and/or separating undesiredmaterial from healthy tissue, such as the walls of a blood vessel, inproximity to the target removal site. Differential cutter assemblies maybe provided, as described in the U.S. patent publications incorporatedherein by reference. Operating heads comprising abrasive rotationalsurfaces may also be used. The operating head, or sub-componentsthereof, such as the cutting surfaces, may be coated with a radio-opaquematerial such as gold, platinum, inks and the like, to render theoperating head radioscopically visible and to assist a medicalprofessional in guiding and positioning the cutter assembly relative toan occlusion.

FIG. 2 illustrates the distal end of one embodiment of an interventionalcatheter of the present invention. In this embodiment, the operatinghead comprises a multi-bladed cutter assembly 50 having a plurality ofraised blades 52 arranged in a radially symmetrical configuration.Blades 52 are preferably differential cutting blades, and cuttingassembly 50 may incorporate a plurality of ports 54 arranged in aradially symmetrical configuration in the spaces between blades 52.Ports 54 are shown provided between each set of neighboring bladestructures in FIG. 2, but it will be appreciated that fewer ports may beprovided. Ports 54 are preferably provided in a generally proximalportion of cutter assembly 50 and may have a generally oblongconfiguration, as illustrated, or may take a variety of otherconfigurations.

The distal end of the interventional catheter illustrated in FIG. 2additionally comprises a large port 56 located in a distal portion ofthe catheter, or a proximal portion of the cutter assembly, proximal toblades 52. Port 56 is generally provided as a window or cut-out in acylindrical structure and preferably spans at least 10% of thecircumference of the structure; more preferably at least 20% thecircumference of the structure; and yet more preferably at least 30% thecircumference of the structure. The cylindrical structure supportingport 56 may be a distal catheter portion, or port 56 may be provided ina generally cylindrical tubular structure mounted, directly orindirectly, to a distal catheter portion 60. In one embodiment,illustrated in FIG. 2, a rigid cylindrical shell 58 is mounted to distalcatheter portion 60 at its proximal end and is mounted to or forms astationary element of bearing 62 at its distal end. Bearing 62 allowsdistal catheter portion 60 and cylindrical shell 58 to remain stationaryduring rotation of cutting assembly 50. Bearing 62 may also providelimited articulation of cutting assembly 50 about its longitudinal axis.

In the embodiment illustrated in FIG. 2, ports 54 may be operated asaspiration or infusion ports and, likewise, enlarged proximal port 56may be operated as an aspiration or infusion port. In one embodiment,proximal port 56 is provided as an aspiration port and communicates withan aspiration lumen within catheter 60 that communicates with aspirationconduit 22, while ports 54 operate as infusion ports and communicatewith an infusion lumen within catheter 60 that communicates withinfusion conduit 26. In another embodiment, port 56 is provided as aninfusion port and communicates with an infusion lumen within catheter 60that communicates with infusion conduit 26, while ports 54 operate asaspiration ports and communicate with an aspiration lumen withincatheter 60 that communicates with aspiration infusion conduit 22.

In another embodiment of an interventional catheter of the presentinvention illustrated in FIG. 3, operating head 70 comprises a distalcutter assembly 72 and a proximal cutter assembly 74 mounted to abearing system 76 that allows rotation of the operating head while thecatheter components proximal to the operating head remain stationary.The interventional catheter illustrated in FIG. 3 additionally comprisesa proximal aspiration port 78 provided as an opening in a cylindricalstructure located proximal to cutter assemblies 72 and 74. Aspirationport 78 communicates with an aspiration lumen within catheter 82 thatcommunicates proximally with aspiration conduit 22. Proximal port 78 maybe provided as an opening or window in a distal catheter portion, or itmay be provided as an opening in a substantially rigid cylindrical shell80. Cylindrical shell 80 is constructed of a generally rigid, durablematerial, such as surgical steel or stainless steel, and has a lengththat is approximately the same as that of each of the cutter assemblies.Shell 80 is generally mounted to, or forms a stationary component of,bearing 76 at its distal end. Bearing 76 allows catheter 82 andcylindrical casing 80 to remain stationary during rotation of operatinghead 50. Bearing 76 may also provide limited articulation of operatinghead 70 about its longitudinal axis.

Aspiration port 78 may be provided as a window spanning at least 15% ofthe circumference of the shell structure; more preferably at least 25%of the circumference of the shell structure; yet more preferably atleast 35% of the circumference of the shell structure. The proximalaspiration port may be provided in a generally ovoid, rectangular, orsquare profile. In certain embodiments, aspiration port 78, which may begenerally oval in shape, has an opening, or surface area that is betweenabout 0.5 to about 20 mm², preferably between about 0.5 and 10 mm² insurface area.

The interventional catheter illustrated in FIG. 3 additionallyincorporates a plurality of infusion ports 85 located proximally withrespect to aspiration port 78, but in proximity to the aspiration portand operating head 70. Infusion ports 85, which may be provided in anouter sheath 84, as shown in FIG. 3, communicate with an infusion lumenin the catheter assembly, which communicates with infusion conduit 26.In certain embodiments, between two and twenty, for example twelve,infusion ports 85 are provided in an infusion sheath 84 mounted todistal catheter 82. The infusion ports may have a generally uniformsize, or infusion ports of different sizes may be provided. The infusionports may be generally cylindrical, as shown in FIG. 3, or they may havealternative configurations. Each infusion port 85 may have a diameter ofapproximately 0.005 in. to 0.20 in., more preferably from about 0.006in. to about 0.015 in. Infusion ports having diameters of about 0.010in. are especially preferred for certain applications. In oneembodiment, the infusion ports are spaced in a generally circumferentialpattern to provide a substantially uniform flow of infusate around thecircumference of the infusion sheath.

In an alternative embodiment, a single infusion port having a surfacearea generally equal to or less than the surface area of the aspirationport may be provided proximally to the aspiration port. A plurality ofinfusion ports may also be spaced relatively closely and arranged toprovide targeted infusion, resulting in a higher volume or pressure ofinfusate at different locations around the circumference of the infusionsheath. Providing a large infusion port, or a series of infusion portsin close proximity to one another allows directional flow of infusateand may facilitate aspiration of debris and/or positioning of theoperating head.

In certain embodiments, the infusion rate and pressure is relativelylow, unlike many prior art systems in which a high rate of fluidinfusion is employed to break-up unwanted material or to guide anoperating head. In many embodiments, for example, the pressure of theinfusion fluid as measured at the infusion pump may from about 80 to 200psi. The volume ratio of infusate to aspirate is also important in manyapplications. In systems of the present invention, the rate of infusionis generally greater than the rate of aspiration. For example, thevolume ratio of infusate to aspirate may be greater than about 1:1 andless than about 3:1. For some applications, the volume ratio of infusateto aspirate may be greater than about 1.5:1 and less than about 2.5:1.In some embodiments, the volume ratio of infusate to aspirate isapproximately 1.5:1, 2:1 or 2.5:1. In certain embodiments, the rate ofinfusion is approximately 45-100 ml/min of device run-time, and the rateof aspiration is approximately 20-60 ml/min of device run-time. Incertain embodiments, the rate of infusion is approximately 45-150ml/min, for example 50-90 ml/min, of device run-time, and the rate ofaspiration is approximately 20-90 ml/min, for example, 20-60 ml/min ofdevice run-time.

Various control and feedback mechanisms may be used in connection withthe aspiration and infusion systems in interventional catheters of thepresent invention. In one embodiment, for example, a bubble detectiondevice is provided in proximity to an infusate conduit and operates todetect gas bubbles in the infusate fluid. An alarm may be triggered upondetection of a bubble, or a control mechanism may inactivate theinfusion and aspiration systems in response to detection of a bubble.Power to the operating head may also be inactivated upon detection of abubble to inactivate the system and prevent introduction of the bubbleinto the patient.

Activation and inactivation of the infusion and aspiration systems maybe controlled by an operator using operator selectable features andcontrols. Alternatively, various operating protocols may be programmedinto the system or provided as selectable features. Operation of theaspiration and infusion systems may be coordinated in a variety of ways,for example, with operation of the operating head. Activation andinactivation of the operating head is generally controlled by theoperator. In one embodiment, the infusion system is primed to ensurethat the infusate conduit is filled with liquid and a reliable supply ofinfusate to infusion ports in proximity to the operating head isestablished prior to guidance of the interventional catheter to the siteof intervention. In one embodiment, the infusate and aspiration systemsare activated automatically upon activation of the operating head. Inanother embodiment, the infusate and aspiration systems are activatedafter a generally short delay period following activation of theoperating head. The infusion and aspiration systems may also beinactivated automatically upon inactivation of the operating head.Alternatively, the infusion and/or aspiration systems may be inactivatedafter a predetermined or selectable time period following inactivationof the operating head. The system may optionally incorporate overridecontrols that allow an operator to override a programmed infusion oraspiration feature.

The present invention has been described with reference to specificdevice embodiments and figures. These specific embodiments should not beconstrued as limitations on the scope of the invention, but merely asillustrations of exemplary embodiments. It is further understood thatmany modifications, additions and substitutions may be made to thedescribed interventional catheter and control system without departingfrom the scope of the present invention.

1. An interventional catheter assembly comprising: (a) a catheter forinsertion and guidance to a target site in a body; (b) a rotationaloperating head mounted in proximity to a distal end of the catheter, theoperating head comprising a plurality of external cutter elements forbreaking down obstructive material into particles at the target site;(c) at least one aspiration port located proximal to the operating headand each of the plurality of external cutter elements, wherein the atleast one aspiration port extends over at least 20% of a circumferenceof the catheter and is in communication with a first sealed lumen forwithdrawing fluids and obstructive material from the target site; and(d) a plurality of infusion ports located proximally with respect to theat least one aspiration port and communicating with an infusion lumen inthe catheter.
 2. The interventional catheter assembly of claim 1,wherein the at least one aspiration port extends over at least 30% ofthe circumference of the catheter.
 3. The interventional catheterassembly of claim 1, additionally comprising an infusion system forsupplying infusion fluid to a location in proximity to the target siteand a wherein the plurality of liquid infusion ports are spacedcircumferentially around the catheter.
 4. The interventional catheterassembly of claim 3, wherein the plurality of liquid infusion ports areuniformly spaced around the circumference of the catheter to providesubstantially even distribution of infusion fluid around thecircumference of the catheter.
 5. The interventional catheter assemblyof claim 3, wherein the plurality of liquid infusion ports arenon-uniformly spaced to direct flow of infusion fluid in at least onedesired direction around the circumference of the catheter.
 6. Theinterventional catheter assembly of claim 1, additionally comprising atleast one port located in the operating head and in communication with asealed lumen for aspiration or infusion of liquid.
 7. The interventionalcatheter assembly of claim 1, additionally comprising: an infusionsystem for providing infusion fluid, wherein the infusion and aspirationsystems are controlled during operation of the interventional catheterassembly to provide volume ratios of infusate to aspirate of greaterthan about 1:1 and less than about 2.5:1.
 8. The interventional catheterassembly of claim 7, wherein the volume ratio of infusion fluid toaspirate is greater than about 1.5:1 and less than about 2.5:1.
 9. Theinterventional catheter assembly of claim 1, additionally comprising atleast one infusion port located proximal to the aspiration port.
 10. Theinterventional catheter assembly of claim 1, additionally comprising: aninfusion system for providing infusion fluid to a location in proximityto the target site, wherein the infusion and aspiration systems arecontrolled during operation of the interventional catheter assembly toprovide an infusion rate of about 45-150 ml/min and an aspiration rateof about 20-90 ml/min.
 11. The interventional catheter assembly of claim1, additionally comprising: an infusion system for providing infusionfluid to a location in proximity to the target site, wherein theaspiration system and the infusion system are automatically inactivatedafter a selected time period following inactivation of the operatinghead.
 12. The interventional catheter assembly of claim 1, wherein thecutter elements are fixed cutting blades.
 13. The interventionalcatheter assembly of claim 1, wherein the cutter elements are adjustablecutting blades.
 14. The interventional catheter assembly of claim 1,wherein the cutter elements are differential cutting blades.
 15. Theinterventional catheter assembly of claim 1, wherein the operating headadditionally comprises an abrasive surface.
 16. The interventionalcatheter assembly of claim 1, wherein the at least one aspiration portis provided as an opening in a substantially rigid cylindrical shell.17. The interventional catheter assembly of claim 16, wherein theoperating head comprises a cutter assembly having a plurality ofexternal cutter elements and the substantially rigid cylindrical shellis approximately the same length as the cutter assembly.
 18. Theinterventional catheter assembly of claim 1, additionally comprising aninfusion system providing infusion fluid distal to the operating head.19. The interventional catheter assembly of claim 1, additionallycomprising an infusion system providing infusion fluid proximal to theoperating head.
 20. The interventional catheter assembly of claim 1,additionally comprising an infusion system having at least one liquidinfusion port providing directional flow of infusate.
 21. Theinterventional catheter assembly of claim 1, additionally comprising aninfusion system providing infusion fluid at pressures of from about 80to 200 psi during operation.
 22. The interventional catheter assembly ofclaim 1, wherein the at least one aspiration port is provided in acylindrical shell structure located proximal to the operating head andeach of the plurality of external cutter elements, wherein thecylindrical shell structure forms a stationary element of a bearing atits distal end and remains stationary relative to the operating headduring rotation of the operating head.